Photographic processes and products employing benzindole phthaleins as optical filter agents

ABSTRACT

This invention relates to a class of phthalein indicator dyes useful as optical filter agents in photographic processes to protect a selectively exposed photosensitive material from further exposure during processing in the presence of incident light. Such dyes comprise 3,3-disubstituted phthalides and 3,3disubstituted naphthalides wherein the 3,3 substituents are benzindole radicals.

PHOTOGRAPI-IICv PROCESSES AND PRODUCTS EMPLOYING BENZINDOLE PHTHALEINSAS OPTICAL FILTER AGENTS BACKGROUND OF THE INVENTION l. Field of theInvention The present invention relates to novel chemical compounds, andmore particularly, it relates to a new class of phthalein indicator dyesand to a method for the preparation thereof.` ln a particular aspect itrelates to certain indole phthaleins useful as optical filter agents inphotographic processes for protecting an exposed photosensitive materialfrom post-exposure fogging during development in the presence ofextraneous incident light and to such photographic uses.

2. Description of the Prior Art A number of photographic processes bywhich images may be developed an'd viewed within seconds or minutesafter exposure have been proposed. Such processes generally employa'processing composition `which is suitably distributed between twosheet-like elements, the desired image being carried by one of saidsheetlike elements. The resulting images may be in blackand-white, e.g.,in silver, or in one or more colors. Processing may be conducted in oroutside of a camera. The most useful of such processes are the diffusiontransfer processes which have been proposed for form.- ing silver or dyeimages, and several of these processes have been commercialized. Suchprocesses have in common the feature that the final image is a function`of the formation of an image-wise distribution of an image-providingreagent and the diffusion transfer of said distribution to or from thestratum carrying the final image, whether positive or negative.

U.S. Pat. No. 3,415,644 discloses a composite photosensitive structure,particularly adapted for use in reflection type photographic diffusiontransfer color processes. This structure comprises a plurality ofessential layers including, in sequence,` a dimensionally stable opaquelayer; one or more silver halide emulsion layers having associatedtherewith dye image-providing material which is soluble and diffusible,in alkali, at a first pH, as a function of the point-to-point degree ofits associated silver halide emulsions exposure to incident actinicradiation; a polymeric layer adapted to receive solubilized dyeimage-providing material diffusing thereto; a polymeric layer containingsufficient acidifying capacity to effect reduction of a processingcomposition from the first pH to a second pH at which the dyeimage-providing material is substantially nondiffusible; and adimensionally stable transparent layer. This structure may be exposed toincident actinic radiation and processed by interposing, intermediatethe silver halide emulsion layer and the reception layer, an alkalineprocessing composition providing the tirst pH and containing alight-reflecting agent, for example, titanium dioxide to provide a whitebackground. The light reflecting agent (referred to in said patent as anopacifying agent) also performs an opacifying function, i.e., it iseffective to mask the developed silver halide emulsions and also acts toprotect the photoexposed emulsions from postexposure fogging by lightpassing v through the transparent layer if the photoexposed film unit isremoved from the camera before image fonnation is complete.

ln a preferred embodiment, the composite photosensitive structureincludes a rupturable container, retaining the alkaline processingcomposition having the first pH and light-reflecting agent, fixedlypositioned extending transverse a leading edge of the compositestructure in order to effect, upon application of compressive pressureto the container, discharge ofthe processing composition intermediatethe opposed surfaces of the reception layer and the next adjacent silverhalide emulsion.

The liquid processing composition distributed intermediate the receptionlayer and the silver halide emulsion, permeates the silver halideemulsion layers of the composite photosensitive structure to initiatedevelopment of the latent images contained therein resultant fromphotoexposure. As a consequence of the development of the latent images,dye image-providing material associated with each of the respectivesilver halide emulsion layers is individually immobilized as a functionof the point-to-point degree of the respective silver halide emulsionlayer photoexposure, resulting in imagewise distributions of mobile dyeimage-providing materials adapted to transfer, by diffusion, to thereception layer to provide the desired transfer dye image. Subsequent tosubstantial dye image formation in the reception layer, a sufficientportion of the ions of the alkaline processing composition transfers, bydiffusion, to the polymeric neutralizing layer to effect reduction inthe alkalinity of the composite film unit to the second pH at which dyeimage-providing material is substantially nondiffusible, and further dyeimageproviding material transfer is thereby substantially obviated.

The transfer dye image is viewed, as a reflection image, through thedimensionally stable transparent layer against the background providedby the reflecting agent, distributed as a component of the processingcomposition, intermediate the reception layer and next adjacent silverhalide emulsion layer. The thus-formed stratum effectively masksresidual dye image-providing material retained in association with thedeveloped silver halide emulsion layer subsequent to processing.

In the copending U.S. Pat. application Ser. No. 786,352 of Edwin H.Land, filed Dec. 23, 1968, now abandoned, and Ser. No. 101,968 filedDec. 28, 1970, now U.S. Pat. No. 3,647,437, in part a continuation ofSer. No. 786,352, an organic light-absorbing reagent (or optical filteragent), such as a dye, which is present as a light-absorbing species atthe first pH and which may be converted to a substantiallynon-light-absorbing species at the second pH is used in conjunction withthe light-reflecting agent to protect the selectively exposed silverhalide emulsions from post-exposure fogging when development of thephotoexposed emulsions is conducted in the presence of extraneousincident actinic radiation impinging on the transparent layer of thefilm unit.

ln copending U.S. Pat. application Ser. No. 108,260 filed Jan. 2l, 1971,now U.S. Pat. No. 3,702,244, pH- sensitive dyes which contain at leastone indole radical bonded by the 2- or 3-position to a ring-closingmoiety are disclosed as useful as optical filter agents for absorbingincident radiation actinic to selectively exposed photosensitivematerials within a predetermined wavelength range in the shorterwavelength region of the visible spectrum. Certain of the novelindicator dyes disclosed therein, namely, phthaleins derived frombenzindoles comprise the subject matter of the present inthatbenzindol-B-yl phthalens are selectively produced. As indicated above,such results are quite unexpected since the formation of abenzindol-3-yl phthalein would be expected either with or without asolvent present on the basis of prior observations reported in theliterature.

The novel indicator dyes produced in accordance with the presentinvention may be defined as phthalens selected from 3,3-disubstitutedphthalides and 3,3- disubstituted naphthalides wherein the 3,3substituents are selected from two benzindol-Z-yl radicals and twobenzindol-3-yl radicals, said benzindolyl radicals having hydrogensubstituted on the heterocyclic nitrogen atom. Typical of the indicatordyes of the present invention are those represented by the formula:

wherein X represents the atoms necessary to complete a ring-closingmoiety selected from a phthalide and a naphthalide.

The indicator dyes defined above and as represented in the foregoingformula may contain substituents on the benzindole radicals and/orring-closing moiety as may be desired which do not interfere with thefunction of the dye for its selected ultimate use. Ordinarily, thebenzindole radicals when substituted are the same, .e., they contain thesame substituents in the same position.

Typical substituents include branched or straight chain alkyl, such as,methyl, ethyl, isopropyl, n-butyl, t-butyl, hexyl, octyl, dodecyl,hexadecyl, octadecyl and eicosanyl; aryl, such as, phenyl,2-hydroxyphenyl, and naphthyl; alkaryl, such as benzyl, phenethyl,phenylhexyl, p-octylphenyl, p-dodecylphenyl; alkoxy, such as, methoxy,ethoxy, butoxy, lethoxy2( ethoxyethoxy), dodecyloxy and octadecyloxy;aryloxy, such as phenoxy, benzyloxy, naphthoxy; alkoxyalkyl, such asmethoxyethyl, dodecyloxyethyl; halo such as, fluoro, bromo, and chloro;trifluoralkyl, such as, trifluoromethyl, monoand bis-trifluoromethylcarbinol; sulfonamido; sulfamoyl; acyl and its derivatives; aminomethyl;amido; sulfonyl; sulfo; cyano; nitro; amino including mono-anddisubstituted amino, e.g., N-ethyl amino and N,N-dimethylamino; carboxy;and hydroxyl.

For use as optical filter agents in photographic processes, such as,diffusion transfer processes employing highly alkaline processingsolutions, it may be desirable that the indicator dye selected as theoptical filter agent possess a relatively high pKa so that the dye willbe in a light-absorbing form during the initial stages of processing andyet may be rendered substantially non-light absorbing within arelatively brief interval as the pH subsequent to substantial imageformation is reduced.

Unsubstituted benzindole phthalens are colored at a relatively high pHand characteristically possess two pKas, one in the neighborhood of 13and a lower one in the neighborhood of I l. Where it is desired to raisethe lower pKa to substantially the same value as the higher pKa so thatthe dye may be rendered colorless more rapidly, a hydrogen-bonding groupcapable of raising the pKa may be substituted in the 9-position of thebenzindol-2-yl radicals and in the 2- and/or 9- position of thebenzindol-S-yl radicals.

The association of two atoms through hydrogen to form a hydrogen bondbetween or within molecules is well known. When hydrogen is attached toan electronegative atom, for example, O or N, the resultant bond ispolarized. If directed toward another atom (M) with an unshared pair ofelectrons, the hydrogen acts as a bridge between the atoms (O-H M) dueto the electrostatic attraction to both atoms between which the hydrogenproton can be transferred. ln the above compounds, an intramolecularhydrogen bond is formed between the -NH- of the benzindole ring and theadjacent hydrogen-bonding group, .e., a group containing a heteroatompossessing an active unshared pair of electrons, such as O, N, S orhalogen, e.g., F., which has a free electron pair or a negative chargein basic solution and which is capable of forming a 5-, 6- or 7-membered and preferably a 5- or -membered hydrogen-bonded ring with the-NH- of the benzindole ring. Preferably, the heteroatom in thehydrogenbonding group has attached to it a proton which is more acidicthan the proton on the NH- of the benzindole and ionizes in basicsolution to a negative charge. Such groups include, for example,carboxy; hydroxy; ortho-hydroxyphenyl and bis trifluoromethyl carbinol;sulfonamido NH-SOz-R wherein R may be alkyl, aryl, alkaryl) andsulfamoyl SOzNHR wherein R may be alkyl, aryl, alkaryl). Suitable R andR' substituents include branched or straight chain alkyl, e.g., methyl,ethyl, isopropyl, n-butyl, t-butyl, hexyl, octyl, dodecyl, hexadecyl,octadecyl and eicosanyl; aryl, e.g., phenyl and naphthyl; and alkaryl,e.g., benzyl, phenethyl, phenylhexyl, p-octylphenyl and pdodecylphenyl.

Where it is desired that the indicator dye be substantially immobile ornon-diffusible in the processing solution, it may be substituted with abulky group, such as, a long chain substituent, e.g., dodecyloxy. When ahydrogen-bonding group is present, the immobilizing function may becombinded with the hydrogenbonding function rather than using a separateimmobilizing group, for example, by selecting sulfonamido or sulfamoylgroups containing as R or R', a substituent, such as, hexadecyl orp-dodecylphenyl.

Specific examples of indicator dyes within the scope of the presentinvention are as follows:

ln preparing the novel dyes according to the method of the presentinvention, the benzindole starting material and the selected acid (orits anhydride or acid chloride) in solution in an inert,high boilingorganic solvent are reacted at elevated temperatures in the presence ofan acid catalyst, for example, toluene-psulfonic acid, phosphorousoxychloride, and preferably, a Lewis acid catalyst. Any of the Lewisacid catalysts conventionally used in the Friedel Crafts reaction may beemployed, for example, aluminum chloride, ferric chloride, stannicchloride, boron trifluoride and zinc chloride.

Besides being inert under the reaction conditions and a solvent for boththe benzindole and phthalic or naphthalic acid reagent, the inertorganic solvent should have a boiling point of at least about 100C. inorder to achieve reasonable product yields. Any inert organic solventmay be used that meets the foregoing criteria, i.e., any inert organicliquid that is capable of dissolving both reactants to form ahomogeneous reaction solution and that has a boiling point of-at leastabout 100C. Particularly useful solvents are toluene and p-xylene'.Generally, the reaction is carried out at refluxing ternperaturesbetween about l-l50C.

The phthalic or naphthalic reagent selected to ultimately form thering-closing moiety may be the acid,

the acid anhydride or the acid chloride. The terms a` phthalic acid andaa naphthalic acid as used herein are intended to include thecorresponding anhydrides and acid chlorides. These acids may besubstituted, with solubilizing groups, such as, carboxy, e.g.,hemimellitic acid; with long chain substituents to adjust the mobilityof the nal dye, e.g., sulfonamido containingv a long chain alkyl groupNH-SOZ-n-CwHaa); or with other substituents as may be desired.

The benzindole starting material, benzo[ 1,2 g]indole, may be preparedusing` any of the conventional reactions available for closing offive-membered heterocyclic rings. A particularly suitable synthesisfollows the route to indole derivatives developed by E. Fischer (Fischerindole synthesis) based on the observation that the phenylhydrazone ofpyruvic acid may be converted into indole-2-carboxylic acid; As anillustration, benzindole was prepared according to the followingreaction sequence; steps a)lirgughw( d).wwww# ii-COOE.

l H A l H (a) To a solution of 25.0 g. (0.23 mole) of sodium pyruvate in200 ml. of water was added a solution of 50.0 g. (0.26 mole) ofa-naphthylhydrazine in 600 ml. of water with vigorous stirring at roomtemperature. After addition was complete, the mixture was allowed tostand at room temperature for about onehalf hour and then chilled. Theprecipitate was removed by suction filtration, washed thoroughly withwater and recrystallized from ethanol to yield 58.0 g. of (A), meltingrange l64l65C.

(b) A suspension of 56.0 g. (0.245 mole) of (A) in lv liter of absoluteethanol was saturated with dry hydrogen chloride gas until ammoniumchloride was cornpletely precipitated. The reaction mixture was heatedon a steam bath for l5 minutes; allowed to stand at room temperature forabout 2 hours; and then poured into 3,000 ml. of crushed ice. Theprecipitate was removed by suction filtration, washed thoroughly withwater and recrystallized from ethanol to yield 47.8 g. of (B), meltingrange l68l69C.

(c) A mixture of 46.0 g. (0.192 mole) of (B), 33.0 g. (0.59 mole) ofpotassium hydroxide, and 800 ml. of ethanol was refluxed for 3 hours.After the mixture cooled to room temperature, it was poured into 2liters of crushed ice and then neutralized with aqueous hydrochloricacid solution. The off-white precipitate was removed by suctionfiltration, washed with cold 50 percent aqueous ethanol and dried invacuo over Drierite at 60C. to yield 40.0 g. of (C), melting range224-225.5C. (d) 28.0 g. (0.13 mole) of (C) was placed in a ml.three-necked round bottom flask fitted with a long reflux condenser anda thermometer. The flask was heated to about 230C. and the resultingmelt was gradually heated to 250-280C. until all of the carbon dioxidehad evolved which took about 45 minutes. At the end of this time, themelt was cooled to room temperature, dissolved in benzene, decolorizedwith Norit and then allowed to crystallize. Upon crystallization a totalof 19.3 g. of (D) was obtained, melting range 169-170C.

Benzindoles containing substituents may be produced following the aboveprocedure, or benzindole, itself, may be subsequently substituted withthe groups desired in the final dye provided the appropriate position isfree to form the 2- or 3- product with the acid reagent. Typical of thesubstituents that may be used are those enumerated above.

The following Examples are given to further illustrate the presentinvention and are not intended to limit the scope thereof.

EXAMPLE 1 Preparation of the compound of formula (1):

A mixture of 3.0 g. (0.018 mole) of benzindole, (benzo[1,2 g]indole),2.0 g. (0.0095 mole) of hemimellitic acid and 300 mg. of freshly fusedzinc chloride in 125 ml. of paraxylene was refluxed for about 72 hours,after which the solvent was removed on a flash evaporator. The residuewas dissolved in 250 ml. of chloroform and chromatographed on a 34X3.6cm. florisil column. The first reaction was eluted with chloroform, andthe second fraction containing the dye was eluted with a 4:1 mixture ofchloroform/methanol. Isolation of the dye by drying in vacuo yielded 100mg. of pure compound.

As discussed above, it is quite unexpected that the benzindol-2-yl dyeis produced under Friedel Craft conditions in the presence of a solventrather than the benzindol-B-yl dye which would be the expected resulteither in the presence or in the absence of a solvent. Apparently, inthe presence of a solvent, reaction in the 2-position of the benzindoleis favored. When the reaction was repeated without p-xylene in anattempt to increase yields, the benzndol-3-yl dye was obtained asdemonstrated in Example 2 below.

EXAMPLE 2 Preparation of the compound of formula A mixture of 0.84 g.(5mm.) of benzindole, 0.5 g. (2.5 mm.) of hemimellitic acid anhydridewas 2.0 g. (14.7 mm) of freshly fused zinc chloride was heated on aheating block at 135140C. for about 5 hours, after which it was washedwith 5 percent aqueous acetic acid solution. The residue was dried invacuo at 60C. over Drierite to yield 0.54 g. of the title compound (80percent by weight pure by sepectroscopy).

The spectral absorption characteristics of the dibenzindol -2-yl7-carboxyphthalide and of the dibenzindol-3-yl 7-carboxyphthalideproduced above are graphically illustrated in the accompanying Figureand are designated therein as (X) and (Y), respectively. The curves for(X) and (Y) represent the optical transmission density, i.e., absorbanceof the respective indicator dyes at a pH substantially above theirrespective pKa as measured in a 1.6 M solution of sodium hydroxide inaqueous ethanol. Curve (Z) represents the spectral absorptioncharacteristics of di-indol-3-yl 7-carboxyphthalide, i.e., the opticaltransmission density as measured under the same conditions. (The laterindole dye was prepared in a conventional manner by refluxing a solutionof indole and hemimellitic anhydride in xylene).

From reference to the FIGURE, it can be seen that the benzindol-S-yl dyeabsorbs radiation over a broader wavelength range than the indol-3-yldye and is a more effective absorber as evidenced by the greater areaunder the curve. As compared to the benzindol-S-yl dye, thebenzindol-2-yl dye has even a broader absorption spectrum that extendswell into the longer wavelength range. Also, it is an especiallyefficient absorber over the extended range as apparent from the shape ofthe spectral curve which is comparatively broad and box-like rather thanpredominantly peaked.

The pKa values measured for the three dyes, (X), (Y) and (Z) illustratedin the Figure were 11.7 and 13.5; 11.0 and 12.5; and 9.1 and 13.3,respectively. Though the values for the higher of the two pKas for eachof the dyes are in substantially the same range, the lower pKa valuesfor both of the benzindole dyes are significantly higher than the lowerpKa value for the indole dye. Because of the substantial increase in thelower pKa which brings the two pKas much closer together, the benzindoledyes may be rendered colorless at a higher pH and thus, may be clearedmore rapidly than the simple indole dye. As noted above, this propertyof clearing relatively rapidly at a comparatively higher pH renders thedyes particularly useful as optical filter agents in photographicprocesses, e.g., diffusion transfer processes where it is desired toview image formation subsequent to the initial stages of developmentemploying highly alkaline processing solutions.

The pH sensitive indicator dyes of the present invention may be used asoptical t'ilter agents in any photographic process includingconventional tray processing and diffusion transfer photographictechniques. ln such l processes, the dye or dyes during development of aselectively exposed photosensitive material will be in a position and ina concentration effective to absorb a given level of non-selectiveradiation incident on and actinic to the photosensitive material. Thedyes may be initially disposed in the film unit, for example, in alayer(s) coextensive with one or both surfaces of the photosensitivelayer. Where selective exposure of the photosensitive material is madethrough a layer containing the indicator dye, then the dyes should be ina non-light-absorbing form until the processing solution is applied.Alternately, the dyes may be initially disposed in the processingcomposition in their lightabsoring form, for example, in the developingbath in tray processing or in the layer of processing solutiondistributed between the photosensitive element and the superposedimage-receiving element (or spreader sheet) in diffusion transferprocessing. The particular indicator dye or dyes selected should have anabsorption spectrum corresponding to the sensitivity of thephotosensitive layer, so as to afford protection over the predeterminedwavelength range required by the particular photosensitive materialemployed and should have a pka such that they are in their colored fomi,i.e., light-absorbing form at the pH at which the photographic processis performed. Most commercially useful photographic processes areperformed under alkaline conditions. Diffusion transfer processes, forexample, usually employ highly alkaline processing solutions having a pHin excess of l2.

In photographic processes where the optical filter agent is retained ina stratum through which the final image is to be viewed, the color ofthe indicator dye may be discharged subsequent to image formation byadjusting the pH of the system to a value at which the dye issubstantially non-light absorbing in the visible spectrum. lnphotographic processes performed at an alkaline pH, the optical filteragent, such as, a dye or dyes of the present invention are renderedsubstantially colorless by reducing the environmental pH. In processeswhere the optical filter agent is removed or separated from the layercontaining the final' image or retained in a layer that does notinterfere with viewing of the final image, it is unnecessary to convertthe indicator dye to its non-light-absorbing form, though the color maybe discharged if desired.

The concentration of indicator dye is selected to provide the opticaltransmission density required, in combination with other layersintermediate the silver halide emulsion layer(s) and the incidentradiation, to prevent nonimagewise exposure, i.e., fogging, by incidentactinic light during the performance of the particular photographicprocess. It has been found, by interposing neutral density (carboncontaining) filters over a layer of titanium dioxide, that atransmission density of approximately 6.0 from said neutral densityfilters was effective to prevent fogging of a diffusion transfermulticolor film unit of the type described in said U.S. Pat. No,3,415,644 having a transparent support layer and an Equivalent ASAExposure Index of approximately 75, when processed for one minute in10,000 foot candles of color corrected light, a light intensityapproximating the intensity of a noon summer sun. The transmissiondensity required to protect such a film unit under the stated conditionsmay also be expressed in terms of the system transmission density of allthe layers intermediate the silver halide layer(s) and the incidentlight; the system transmission density required to protect color filmunits of the aforementioned type and photographic speed has been foundto be on the order of 7.0 to 7.2. Lesser levels of optical transmissiondensity would, of course, provide effective protection for shorterprocessing times, lesser light intensities and/or films having lowerexposure indices. The transmission density and the indicator dyeconcentration necessary to provide the requisite protection fromincident light may be readily determined for any photographic process byfollowing the above described procedure or obvious modificationsthereof.

Since most commercial photographic processes employ photosensitivematerials sensitive to and exposable to actinic radiation throughout thevisible spectrum, e.g., black-and-white panchromatic silver halideemulsions and multilayer silver halide emulsion elements, it ispreferred to use a second dye(s) in conjunction with the subject dye( s)that has a principal absorption in a second and at least partiallydifferent predetermined wavelength range such that the combination ofdyes will afford protection from non-selective incident actinicradiation over the range of 400 to 700 nm. The second dye employed maybe non-colorchanging but preferably, is also pH sensitive, i.e., hasreversibly alterable spectral absorption*characteristics in response tochanges in the environmental pH so that it may be renderedlight-absorbing or non-light-absorbing as desired. Illustrative of suchdyes are phthaleins derived from phenols, such as, thymol phthalein. Thesecond dye also may be initially present in the film unit or in theprocessing composition as discussed above either together with orseparate from the subject dyes and subsequent to processing may beremoved from the film unit or retained within the film structure,provided it is in a form or position such that it does not interferewith viewing of the image produced.

The dyes of the present invention are especially useful as opticalfilter agents in diffusion transfer processes, for example, thoseemploying composite diffusion transfer photosensitive elements includinga film pack or roll wherein superposed photosensitive andimage-receiving elements are maintained as a laminate after formation ofthe final image. Such elements include at least one transparent supportto allow viewing of the final image without destroying the structuralintegrity of the film unit. Preferably, the support carrying thephotosensitive layer(s) is opaque and the support carrying theimage-receiving layer is transparent and selective photoexposure of thephotosensitive layer(s) and viewing of the final image both are effectedthrough the latter support. The final image is viewed as a reflectionprint, i.e., by refiected light, provided by a reflecting agentinitially disposed in the processing composition applied and maintainedintermediate the image-receiving and next adjacent photosensitive layeror by a preformed layer of reflecting agent initially positionedintermediate the image-receiving and next adcacent photosensitive layer.lt will be understood that a preformed refiecting layer, while it shouldbe capable of masking the photosensitive layer(s) subsequent to imageformation, should not interfere with selective photoexposure of thephotosensitive material prior to processing. v

When utilizing reflection-type composite film units, the indicator dyeor dyes employed as the optical filter agent(s) may be positionedinitially in a layer of the film unit, e.g., in a layer between theimage-receiving and next adjacent photosensitive layer through whichphoto-exposure is effected provided it is incorporated under conditions,i.e., at a pH such that it will not absorb actinic radiation intended toselectively expose the photosensitive material to form a latent imagetherein. For example, the optical filter agent may be in a layer coatedover either the image-receiving layer or the next adjacentphotosensitive layer and should remain substantially non-light-absorbinguntil a processing composition is applied providing a pH at which theindicator dye is capable of being rapidly converted to itslightabsorbing form to provide light protection when the film unit isremoved from the camera. Rather than being initially disposed in thefilm unit, the indicator dye may be initially present in the processingcomposition applied intermediate the image-receiving and next adjacentphotosensitive layer subsequent to photoexposure. The dye, wheninitially disposed in the processing composition, will be in itslight-absorbing form.

The dyes selected as optical filter agents should ex- ,hibit at theinitial pH of the processing, maximum spectral absorption of radiationat the wavelengths to which the film units photosensitive silver halidelayer or layers are sensitive, and preferably, should be substantiallyimmobile or non-diffusible in the alkaline processing composition inorder to achieve optimum efficiency as a radiation filter and to preventdiffusion of filter agent into layers of the film unit where itspresence may be undesirable. Recognizing that the filter agentabsorption will detract from image-viewing characteristics bycontaminating reflecting pigment background, the selected agents shouldbe those exhibiting major spectral absorption at the pH at whichprocessing is effected and minimal absorption at a pH below that whichob tains during transfer image formation` Accordingly, the selectedoptical filter agent or agents should possess a pKa below that of theprocessing pH and above that of the environmental pH subsequent totransfer image formation.

As discussed previously, the concentration of indicator dye is selectedto provide the optical transmission density required, in combinationwith other layers intermediate the silver halide emulsion layer(s) andthe incident radiation, to prevent nonimagewise exposure, i.e., fogging,by incident actinic light during the performance of the particularphotographic process. ln the processes where the indicator dye or dyesselected as optical filter agents are used in conjunction with arefleeting agent or agents, the optical filter agents and reflectingagents together should possess the optical transmission densitynecessary to protect the photosensitive material for the particularphotographic process. The optimum concentration of optical filteragent(s) or filter agent(s) together with reflecting agent(s) may bereadily determined empirically for each photographic system.

While substantially any reflecting agent may be employed for the layerof reflecting agent, either preformed or applied as a component of theprocessing composition, it is preferred to select an agent that will notinterfere with the color integrity of the dye transfer image, as viewedby the observer, and, most preferably, an agent which is aestheticallypleasing to the viewer and does not provide a background detracting fromthe information content of the image. Particularly desirable reflectingagents will be those providing a white background, for viewing thetransfer image, and specifically those conventionally employed toprovide background for reflection photographic prints and, especially,those agents possessing the optical properties desired for reflection ofincident radiation.

As examples of reflecting agents, mention may be made of barium sulfate,zinc sulfide, titanium dioxide, barium stearate, silver flake,silicates, alumina, zirconium oxide, zirconium acetyl acetate, sodiumzirconium sulfate, kaolin, mica, and the like.

Illustrative of the photographic use of the indicator dyes of thepresent invention as optical filter agents, a photographic film unit maybe prepared by coating, in succession, on a gelatin subbed, 4 mil.opaque polyethylene terephthalate film base, the following layers:

l. a layer of the cyan dye developer 1,4-bis-(-[hydroquinonyl-a-methyl]-ethylamino)5,S-dihydroxyanthraquinone dispersedin gelatin and coated at a coverage of about 80 mgs./ft.2 of dye andabout 100 mgs./f t.2 of gelatin;

2. a red-sensitive gelatino-silver iodobromide emulsion coated at acoverage of about 225 mgs./ft.2 of silver and about 50 mgs./ft.2 ofgelatin;

3. a layer of the acrylic latex sold by Rohm and Haas Co., Philadelphia,Pa., U.S.A., under the trade designation AC-6l and polyacrylamide coatedat a coverage of about 150 mgs./t`t.2 of AC-6l and about 5 mgs/ft.2 ofpolyacrylamide;

4. a layer of the magenta dye developer 2-(p-[-hydroquinonylethyll-phenylazo )4isopropoxy l naphthol dispersed ingelatin and coated at a coverage of mgs./ft.2 of dye and about 120mgs./ft.2 of gelatin;

5. a green-sensitive gelatino-silver iodobromide emulsion coated at acoverage of about 120 mgs./ft.2 of silver and 60 mgs./ft." of gelatin;

6. a layer comprising the acrylic latex sold by Rohm and Haas Co. underthe trade designation B-l5 and polyacrylamide coated at a coverage ofabout 100 mgs- ./ft.2 of B-l5 and about l0 mgs./ft.2 of polyacrylamide;

7. a layer of the yellow dye developer 4-(p[hydroquinonylethyl]-phenylazo)3(N-n-hexylcarboxamido)-l-phenyl-S-pyrazolone and the auxiliary developer 4'methylphenylhydroquinone dispersed in gelatin and coated at a coverage of about 50mgs./ft.2 of dye, about 15 mgs./ft.2 of auxiliary developer and 50mgs./ft.2 of gelatin;

8. a blue-sensitive gelatino-silver iodobromide emulsion coated at acoverage of about mgs./ft.2 of silver and about 75 mgs./ft.2 of gelatin;and

9. a layer of gelatin coated at a coverage of about 50 mgs./ft.2 bygelatin.

Then a transparent 4 mil. polyethylene terephthalate film base may becoated, in succession, with the following illustrative layers:

1. a 7:3 mixture, by weight, of polyethylene/maleic acid copolymer andpolyvinyl alcohol at a coverage of about 1400 mgs./ft.2, to provide apolymeric acid layer;

2. a graft copolymer of acrylamide and diacetone acrylamide on apolyvinyl alcohol backbone in a molar ratio of 113.221 at a coverage ofabout 800 mgs./ft.2, to provide a polymeric spacer layer; and

3. a 2:1 mixture, by weight, of polyvinyl alcohol andpoly-4-vinylpyridine, at a coverage of about 900 mgs./f t.2 andincluding about 20 mgs./ft.2 phenyl mercapto tetrazole, to provide apolymeric image-receiving layer.

The two components thus prepared may then be taped together in laminateform, at their respective edges, by means of a pressure-sensitivebinding tape extending around, in contact with, and over the edges ofthe resultant laminate.

A rupturable container comprising an outer layer of lead foil and aninner liner or layer of polyvinyl chloride retaining an aqueous alkalineprocessing solution comprising:

Potassium hydroxide 1 1.2 gms.

Hydroxyethyl cellulose (high viscosity) [commercially available fromHercules Powder Co., Wilmington, Delaware, under the trade name Natrasol250] 3.4 gms.

N-phenethyl-a-picolinium bromide 2.7 gms.

Benzotriazole 1.15 gms.

Titanium dioxide 50.0 gms.

2.0 gms.

l C O-CH;

may then be fixedly mounted on the leading edge of each of thelaminates, by pressure-sensitive tapes interconnecting the respectivecontainers and laminates, such that, upon application of compressivepressure to a container, its contents may be distributed, upon ruptureof the containers marginal seal, between the polymeric image-receivinglayer and next adjacent gelatin layer.

The photosensitive composite film units may be exposed through stepwedges to selectively filter radiation incident on the transparentpolyethylene terephthalate layer and processed by passage of the exposedfilmv units through appropriate pressure-applying members, such assuitably gapped, opposed rolls, to effect rupture of the container anddistribution of its contents. During processing, the multicolor dyetransfer image formation may be viewed through the transparentpolyethylene terephthalate layer against the titanium dioxide backgroundprovided by distribution of the pigment containing processingcomposition between the polymeric image-receiving layer and gelatinlayer 9 of the photosensitive component. The film unit may be exposed toincident light and the formation of the image may be viewed upondistributionV of the processing composition by reason of the protectionagainst incident radiation afforded the photosensitive silver halideemulsion layers by the optical filter agents and by reason of theeffective reflective background afforded by the titanium dioxide.

lt will be recognized that the benzindol-2-yl phthaleins of the presentinvention, such as, the compound prepared in Example 1 may be employedas optical filter agents in photographic processes, for example, asillustrated above.

The film unit detailed above is similar to that shown in FIG. 2 andrelated FIGS. 3 and 4 of aforementioned copending U. S. Pat. applicationSer. No. 101,968. The negative component of the film unit including thephotosensitive strata and associated dye-image-forming` material; thepositive component includingthe timing, neutralizing and dyeable layers;and the processing composition including its components, such as, thealkaline material and various addenda are described in detail inapplication Ser. No. 101,968. For convenience, the specification of thisapplication is specifically incorporated herein.

Besides the above photosensitive element, the dyes of the presentinvention may be employed in composite photosensitive elements, ingeneral, where the dyeable stratum along with any associated layers maybe contained together with the photosensitive strata as a unitary filmunit which may be termed an integral negative-positive film unitcomprising a negative component including the aforementioned essentiallayers and a positive component including at least the dyeable stratumin which the color transfer image is to be formed. The essential layersare preferably contained on a transparent dimensionally stable layer orsupport member positioned closest to the dyeable stratum so that theresulting transfer image is viewable through this transparent layer.Most preferably another dimensionally stable layer which may betransparent or opaque is positioned on the opposed surface of theessential layers so that the aforementioned essential layers aresandwiched or confined between a pair of dimensionally stable layers orsupport members, at least one of which is transparent to permit viewingtherethrough of a color transfer image obtained as a function ofdevelopment of the exposed film unit in accordance with the known colordiffusion transfer processes. It will be appreciated that all of thesefilm units, like the specific one detailed above, may optionally containother layers performing specific desired functions, e.g., spacer layers,pli-reducing layers, etc.

Exmaples of such integral negative-positive film units for preparingcolor transfer images viewable without separation are those describedand claimed in aforementioned U. S. Pat. No. 3,415,644 and in U. S. Pat.Nos. 3,415,645, 3,415,646, 3,473,925, and 3,573,043.

In general, the film units of the foregoing description, e.g., thosedescribed in the aforementioned patents and/or copending applications,are exposed to form a developable image and thereafter developed byapplying the appropriate processing composition to develop exposedsilver halide and to form, as a function of development, an imagewisedistribution of diffusible dye image-providing material which istransferred, at least in part by diffusion, to the dyeable stratum toimpart thereto the desired color transfer image, e.g., a positive colortransfer image. Common to all of these systems is the provision of areflecting layer between the dyeable stratum and the photosensitivestrata to mask effectively the latter and to provide a background forviewing the color image contained in the dyeable stratum, whereby thisimage is viewable without separation, from the other layers or elementsof the film unit.

` As discussed previously, in some embodiments this reflecting layer isprovided prior to photoexposeure, e.g., as a preformed layer included inthe essential layers of the laminar structure comprising the film unit,and in others it is provided at some time thereafter, e.g., by includinga suitable light-reflecting agent, for example, a white pigment, suchas, titanium dioxide, in the processing composition. As an example ofsuch a preformed layer, mention may be made of that disclosed in thecopending applications of Edwin H. Land, Ser. Nos. 846,441 filed July31, 1969, and 3,645, filed Jan. 19, 1970 and now U. S. Pat. Nos.3,615,421 and 3,620,724, respectively. The reflecting pigment may begenerated in situ as is disclosed in the copending applications of EdwinH. Land, Ser. Nos. 43,741 and 43,742, both filed June 5, 1970 and nowU.S. Pat. Nos. 3,647,434 and 3,647,435, respectively. 1n a particularlypreferred form, such film units are employed in conjunction with arupturable container, such as, that used above, containing theprocessing composition having the light-reflecting agent incorporatedtherein which container is adapted upon application of pressure ofdistributing its contents to develop the exposed film unit and toprovide the light-reflecting layer.

As noted previously, the photographic use of the dyes of the presentinvention as optical filter agents to prevent post-exposure fogging of aselectively exposed photosensitive material is not limited to diffusiontransfer processes nor to such processes employing compositephotosensitive elements. While the use of such dyes in compositemulticolor diffusion transfer film units is a particularly preferredembodiment of the present invention, these dyes may be used with equallyeffective results in any photographic process where it is desired toprotect a photosensitive material from incident radiation actinic to thephotosensitive material within the wavelength range capable of beingabsorbed by the dye. For example, the subject dyes may be used inconventional tray photographic processing as a component of theprocessing bath, or they may be present in a layer coextensive with oneor both surfaces of a layer or photosensitive material to be processedusing conventional tray procedures, provided that they arenon-lightabsorbing prior to photoexposure and also subsequent todeveloping the latent image unless the layer containing the dye is to beremoved subsequent to processing. 1n such procedures, the photoexposedphotosensitive material will, ofcourse, be transferred from the camerato the processing bath in the absence of radiation actinic to thematerial.

The subject dyes also may be employed in diffusion transfer processeswhere the photosensitive and imagereceiving elements are separatedsubsequent to the formation of a transfer image or where a spreadersheet is separated from the photosensitive element to reveal a finalimage in the negative. 1N addition to the composite diffusion transferstructures described above, the subject dyes may be used with compositediffusion transfer film units where the final image is to be viewed bytransmitted light. Also they may be used in composite film unitsspecifically adapted, for example, for forming a silver transfer image,for developing a negative silver image by monobath processing, forobtaining an additive color image, and for obtaining a dye image by thesilver dye bleach process which structures are described in detail inaforementioned copending U. S. application Ser. No. 101,968,particularly with reference to FIGS. l to 13 ofthe applicationsdrawings.

Although the invention has been discussed in detail throughout employingdye developers, the preferred image-providing materials, it will bereadily recognized that other, less preferred, image-providing materialsmay be substituted in replacement of the preferred dye developers in thepractice of the invention. For example, there may be employed dyeimage-forming materials such as those disclosed in U. S. Pat. Nos.2,647,049;

3,352,672; 3,364,022; 3,443,939; 3,443,940; 3,443,941; 3,443,943; etc.,wherein color diffusion transfer processes are described which employcolor coupling techniques comprising, at least in part, reacting one ormore color developing agents and one or more color formers or couplersto provide a dye transfer image to a superposed image-receiving layerand those disclosed in U. S. Pat. No. 2,774,668 and 3,087,817, whereincolor diffusion transfer processes are described which employ theimagewise differential transfer of complete dyes by the mechanismstherein described to provide a transfer dye image to a contiguousimage-receiving layer, and thus including the employment ofimage-providing materials in whole or in part initially insoluble ornondiffusible as disposed in the film unit which diffuse duringprocessing as a direct or indirect function of exposure.

In view of the foregoing, it will be readily apparent that the subjectdyes are useful generally in photographic processes for producingsilver, monochromatic and multi-color images using any photosensitivematerial including conventional and direct positive silver halideemulsions. Depending upon the selected photosensitive material, one ormore of the dyes may be used alone or in combination with anotheroptical filter agent, such as another light-absorbing dye, which seconddye may be non-color-changing or another pH sensitive dye. If theselected dye or dyes do not possess the desired stability in theprocessing composition for long term storage therein, they may beinitially disposed in the film structure or stored in adouble-compartmented pod or in one of two associated pods separate fromthe processing solution until such time as the pod(s) are rupturedwhereupon the dyes are admixed with the processing solution.

Since certain changes may be made in the above product and processwithout departing from the scope of the invention herein involved, it isintended that all matter contained in the above description or shown inthe accompanying drawings shall be interpreted as illustrative and notin a limiting sense.

What is claimed is:

l. A photographic process comprising the steps of selectively exposing aphotosensitive element comprising a layer of photosensitive material toradiation actinic thereto to provide a latent image therein, applying aprocessing composition to provide an indicator dye in a form capable ofabsorbing a predetermined wavelength range of radiation actinic to saidphotosensitive material, and developing said latent image while exposingsaid photo-sensitive element non-selectively to incident actinicradiation within said predetermined wavelength range, said indicator dyebeing present during development in a position and quantity effective toabsorb said wavelength range of incident radiation in an amountsufficient to prevent any substantial increase, as a result ofperforming said process in the presence of incident radiation withinsaid wavelength range, in the minimum density of the image obtained bysaid development of said latent image, and being selected from a3,3-disubstituted phthalide and a 3,3- disubstituted naphthalide whereinthe 3,3 substituents are selected from two benzindol-Z-yl radicals andtwo benzindol-3-yl radicals.

2. A process as defined in claim l wherein said indicator dye isinitially disposed in said processing composition having a pH at whichsaid indicator dye is lightabsorbing, said processing composition beingapplied to said photosensitive layer and said composition containingsaid indicator dye being separated from the photosensitive layersubsequent to substantial image development.

3. A process as defined in claim l wherein said indicator dyeis'retained in said element and is rendered ineffective to preventviewing of the final image subsequent to substantial image developmentby adjusting the pH of said indicator dyes environment to a value atwhich it is substantially non-light-absorbing.

4. A process as defined in claim 3 wherein said indicator dye isinitially present in a processing composition permeable layer at a pHvalue at which it is substantially non-light absorbing, said layer beingcoextensive with at least one surface of said photosensitive layer andsaid processing composition applied thereto having a pH at which saidindicator dye is lightabsorbing.

5. A process as defined in claim 1 wherein said layer of photosensitivematerial is a silver halide layer.

6. A process as defined in claim 1 wherein said indicator dye is a3,3-disubstituted phthalide.

7. A process as defined in claim 6 wherein said 3,3 substituents are twobenzindol-Z-yl radicals.

8. A process as defined in claim 6 wherein said 3,3 substituents are twobenzindol-3-yl radicals.

9. A process as defined in claim 6 wherein said indicator dye isdi-benzindol-Z-yl 7-carboxyphthalide.

l0. A process as defined in claim 6 wherein said indicator dye isdi-benzindol-3-yl 7-carboxyphthalide.

11. A process of forming photographic diffusion transfer images whichcomprises, in combination, the steps of:

a. exposing a photographic film unit which comprises a plurality oflayers including an opaque support layer carrying a photosensitivesilver halide layer having associated therewith a compound capable ofproviding as a function of development an imagewise distribution of animage-forming material which is processing composition soluble anddiffusible as a function of the point-to-point degree of exposure ofsaid silver halide layer and a diffusion transfer processimage-receiving layer adapted to receive solubilized image-formingmaterial diffusing thereto;

b. contacting said photosensitive silver halide layer with an aqueousalkaline processing composition to provide an indicator dye in a formcapable of absorbing a predetermined wavelength range of radiationactinic to said photosensitive material, said indicator dye beingselected from a 3,3- disubstituted phthalide and a 3,3-disubstitutednaphthalide wherein said 3,3 substituents are selected from twobenzindol-2-yl radicals and two benzidol-S-yl radicals.

c. effecting thereby development of said silver halide emulsion;

d. forming thereby an imagewise distribution of diffusible image-formingmaterial, as a function of the point-to-point degree of emulsionexposure; and

e. transferring, by diffusion, at least a portion of said imagewisedistribution of diffusible image-forming material to said layer adaptedto receive said material to provide an image therein; said indicator dyebeing present during development in a position and quantity effective toabsorb said wavelength range of actinic radiation in an amountsufficient to prevent any substantial decrease, as a result ofperforming said process in the presence of incident actinic light withinsaid wavelength range, in the maximum density of the image obtained bythe transfer of said diffusible image-forming material.

l2. A process of forming transfer images as defined in claim 11 whereinsaid indicator dye is disposed, at a pH below its pKa, in a separateprocessing composition permeable layer and said photosensitive silverhalide layer is positioned intermediate said opaque support and saidlayer containing said indicator dye.

13. A process of forming transfer images in color which comprises, incombination, the steps of:

a. exposing a photographic film unit which is adapted to be processed byapplication of pressure to release and distribute a processingcomposition and which includes, in combination, a photosensitive elementcomprising a composite structure containing, as essential layers, insequence, a first support layer opaque to incident actinic radiation; aphotosensitive silver halide layer having associated therewith acompound capable of providing as a function of development an imagewisedistribution of a dye image-forming material which is processingcomposition soluble and diffusible as a function of exposure of thephotosensitive silver halide layer to actinic radiation; a polymericlayer dyeable by said dye image-forming material; a second support layertransparent to indicent actinic radiation; and means securing saidlayers in substantially fixed relationship; means for interposing areflecting agent and an indicator dye capable of absorbing incidentradiation within a predetermined wavelength range actinic to saidphotosensitive layer at a pH above its pKa intermediate said dyeablepolymeric layer and said photosensitive silver halide layer andassociated dye image-forming material subsequent to photoexposure ofsaid film unit, said indicator dye being selected from a3,3-disubstituted phthalide and a 3,3-disubstituted naphthalide whereinsaid 3,3 substituents are selected from two benzindol- 2-yl radicals andtwo benzindol-S-yl radicals;

a rupturable container retaining an aqueous alkaline processingcomposition possessing a pH above the pKa of said indicator dye fixedlypositioned and extending transverse a leading edge of saidphotosensitive element to effect unidirectional discharge of thecontainers processing composition intermediate said dyeable polymericlayer and the photosensitive silver halide layer next adjacent theretoupon application of compressive force to said container:

b. applying compressive force to said rupturable container to effectunidirectional discharge of the containers processing compositionintermediate said dyeable polymeric layer and said photosensitive silverhalide layer;

c effecting thereby substantial development of said silver halide layerand disposition of said reflecting agent and said indicator dye at a pHabove its pKa intermediate said dyeable polymeric layer and saidphotosensitive silver halide layer;

d. as a result of said development, forming an imagewise distribution ofdiffusible dye image-forming material, as a function of thepoint-to-point degree of exposure of said photosensitive layer; e.transferring, by diffusion, at least a portion of said imagewisedistribution of diffusible dye image-forming material to said dyeablepolymeric layer to provide a dye image thereto; and maintaining saidcomposite structure in tact subsequent to said processing, saidindicator dye being present in a quantity effective to absorb saidwavelength range of incident radiation in an amount sufficient incombination with said reflecting agent, to prevent any substantialdecrease, as a result of performing said process in the presence ofincident actinic light within said wavelength range, in the maximumdensity of the image obtained by the transfer of said diffusibleimage-forming material.

14. A process of forming transfer images in color as defined in claim 13wherein said indicator dye is initially disposed at a pH below its pKain an aqueous alkaline processing composition permeable layer of saidphotosensitive element intermediate said dyeable polymeric layer andsaid silver halide layer, and said rupturable container containing saidaqueous alkaline processing composition possessing a pH above the pKa ofsaid indicator dye is fixedly positioned and extends transverse aleading edge of said photosensitive element to effect unidirectionaldischarge of the processing composition intermediate said dyeablepolymeric layer and said layer containing said indicator dye uponapplication of compressive force to said container and including thestep of discharging said processing composition, subsequent to exposureof said photosensitive element, intermediate said dyeable polymericlayer and said layer containing said indicator dye.

15. A process of forming transfer images in color as defined in claim 13wherein said reflecting agent is titanium dioxide and said indicator dyeand said titanium dioxide are initially disposed in said aqueousalkaline processing composition as retained in said rupturablecontainer.

16. A process of forming transfer images in color as defined in claim 13wherein said photosensitive element includes at least one acid reactingpolymeric layer positioned intermediate at least one of (a) said firstopaque layer and the photosensitive silver halide layer next adjacentthereto, and (b) said second transparent layer and the dyeable polymericlayer next adjacent thereto, and contains sufficient acidifying functionto effect reduction of said aqueous alkaline processing composition froma pH above to a pH below the pKa of said indicator dye and including thestep of transferring, by diffusion, subsequent to substantial transferdye image formation, a sufficient portion of the ions of said processingcomposition to said polymeric acid layer to thereby reduce said pH to apH below said pKa.

17. A process of forming transfer images in color as defined in claim 16wherein said dye-image forming material comprises a dye which is asilver halide developing agent and said photosensitive layer is a silverhalide emulsion.

18. A process of forming transfer images in color as defined in claim 17wherein said photosensitive element comprises at least two selectivelysensitized silver halide emulsion layers, each of said layers havingassociated therewith an image-forming dye, which is a silver halidedeveloping agent, of predetermined color, and is soluble and diffusible,in aqueous alkaline processing composition as a function of thepoint-to-point degree of exposure of the respective emulsion associatedtherewith.

19. A process of forming transfer images in color as defined in claim 13wherein said photosensitive element comprises three selectivelysensitized silver halide emulsion layers on said support, in sequence, aredsensitive silver halide emulsion layer having associated therewith acyan image-forming dye; a green-sensitive silver halide emulsion layerhaving associated therewith a magenta image-forming dye; ablue-sensitive silver halide emulsion layer having associated therewitha yellow image-forming dye; each of said cyan, magenta and yellowimage-forming dyes being silver halide developing agents and soluble anddiffusible in said aqueous alkaline processing solution.

20. A process as defined in claim 13 wherein said indicator dye is a3,3-disubstituted phthalide.

21. A process as defined in claim 20 wherein said 3,3 substituents arebenzindol-Z-yl radicals.

22. A process as defined in claim 20 wherein said 3,3 substituents arebenzindol-3-yl radicals.

23. A process as defined in claim 13 wherein said indicator dye isdi-benzindol-Z-yl 7-carboxyphthalide.

24. A process as defined in claim 13 wherein said indicator dye isdi-benzindol-3-yl 7-carboxyphthalide.

25. A photographic film unit which comprises a plurality of layersincluding a support layer carrying on one surface, in order a layer ofphotosensitive material and a layer comprising an indicator dye disposedat a pH below its pKa selected from a 3,3-disubstituted phthalide and a3,3-disubstituted naphthalide wherein said 3,3 substituents are selectedfrom two benzindol- 2-yl radicals and two benzindol-3-yl radicals.

26. A photographic film unit as defined in claim 25 wherein saidphotosensitive material is silver halide.

27. A photographic film unit as defined in claim 25 wherein said silverhalide layer has associated therewith a silver halide developing agent.

28. A photographic film unit as defined in claim 25 wherein said silverhalide layer has associated therewith a dye-providing compound capableof providing as a function of development an imagewisc distribution of adye image-forming material which is processing composition soluble anddiffusible as a function of the point-to-point degree of exposure ofsaid silver halide layer.

29. A photographic film unit as defined in claim 28 which is adapted tobe processed by application of pressure to release and distribute aprocessing composition and which comprises, in combination:

a photosensitive element including a composite structure containing, asessential layers, in sequence, a first support layer opaque to incidentactinic radiation; at least two selectively sensitized silver halidelayers, each having associated therewith an image-forming dye which is asilver halide developing agent of predetermined color, each of said dyesbeing soluble and diffusible in alkaline processing composition as afunction of the pointto-point degree of exposure of the respectivesilver halide associated therewith, a polymeric layer dyeable by saiddye; a second support layer transparent to incident actinic radiation;and means securing said layers in substantially fixed relationship;

a rupturable container retaining an alkaline processing compositioncontaining reflecting agent fixedly positioned and extending transversea leading edge of said photosensitive element to effect unidirectionaldischarge of said container's processing composition between saiddyeable polymeric layer and the photosensitive silver halide layer nextadjacent therto upon application of pressure to said container; and anindicator dye capable of absorbing incident radiation within apredetermined wavelength range actinic to said silver halide disposed inat least one of said processing composition and, at a pH below its pKa,in a layer intermediate said photosensitive silver halide layer and saidsecond support layer transparent to incident actinic radiation, saidindicator dye being selected from a` 3,3-disubstituted phthalide and a3,3-disubsttuted naphthalide wherein said 3,3 substituents are selectedfrom two benzindol-2-yl radicals and two benzindol-S-yl radicals.

30. A photographic film unit as defined in claim 29 including at leastone acid reacting polymeric layer positioned intermediate at least oneof said first opaque layer and the photosensitive silver halide layernext adjacent thereto, and said second transparent layer and the dyeablepolymeric layer next adjacent therto, said polymeric acid layercontaining sufficient acidifying function to effect reduction of saidprocessing composition from a first pH at which said image-forming dyeis substantially soluble and diffusible to a second pH at which saidimage-f`orming dye is substantially nondiffusible.

31. A photographic film unit as defined in claim 30 wherein saidreflecting agent taken together with said indicator dye are adapted toprevent further exposure of the selectively exposed silver halide layerduring processing in the presence of radiation within said predeterminedwavelength range actinic to the silver halide layer and incident on thesurface of the film unit opposite to the opaque support layer.

32. A photographic film unit as defined in claim 31 wherein saidphotosensitive element includes, as essential layers, in sequence, fromsaid opaque support layer, an alkaline solution permeable polymericlayercontaining a cyan dye; a red-sensitive silver halide emulsion layer; analkaline solution permeable polymeric layer containing a magenta dye; agreen-sensitive silver halide emulsion layer; an alkaline solutionpermeable polymeric layer containing a yellow dye; a bluesensitivesilver halide emulsion layer, each of said cyan, magenta and yellow dyesbeing silver halide developing agents and being soluble and diffusible,in aqueous alkaline solution at said first pH and substantially insoluble in aqueous alkaline solution at said second pH.

33. A film unit as defined in claim 29 wherein said indicator dye is a3,3-disubstituted phthalide.

34. A film unit as defined in claim -yl wherein said 3,3 substituentsare benzindol-Zyl radicals.

35. A film unit as defined in claim 33 wherein said 3,3 substitutent arebenzindol-3-yl radicals.

36. A film unit as defined in claim 29 wherein said indicator dye isdi-benzindol2yl 7-carboxyphthalide.

37. A film unit as defined in claim 29 wherein said indicator dye isdi-benzindol-3-yl '7-carboxyphthalide.

38. A photographic processing composition comprising an aqueous alkalinesolution of a viscosity imparting reagent, a light-reflecting agent andan indicator dye selected from a 3,3-disubstituted phthalide and a3,3-disubstituted naphthalide wherein said 3,3 substituents are selectedfrom two benzindol-2-yl radicals and two benzindol-3-yl radicals.

39. A photographic processing composition as de fined in claim 38 whichadditionally contains a silver halide developing agent.

40. A composition as defined in claim 38 wherein said indicator dye is a3,3-disubstituted phthalide.

4l. A composition as defined in claim 40 wherein said 3,3 substituentsare benzindol 2yl radicals.

42. A composition as defined in claim 40 wherein said 3,3 substituentsare benzindol-3yl radicals.

43. A composition as defined in claim 38 wherein said indicator dye isdi-benzindol-Z-yl 7-carboxyphtha lide.

44. A composition as defined in claim 38 wherein said indicator dye isdi-benzindol-3-yl 7-carboxyphtha lide.

4S. A composition as defined in claim 38 wherein said aqueous alkalinesolution has a pH above the pKa United States Patent [191 Bloom et al.

[45] Dec. 18, 1973 [54] PHOTOGRAPHIC PROCESSES AND PRODUCTS EMPLOYINGAMlNOMETHYL-SUBSTITUTED PHENOLIC PHTHALEINS As OPTICAL FILTER AGENTS[75] Inventors: Stanley M. Bloom, Waban; Elbert M. Idelson, Newton LowerFalls;

Myron S. Simon, West Newton; David P. Waller, Arlington, all of Mass.

[73] Assignee: Polaroid Corporation, Cambridge,

Mass.

[22] Filed: Sept. 2, 1971 [2l] Appl. No.: 177,497

[52] U.S. Cl. 96/3, 96/29 D, 96/84 R [5l] Int. Cl. G03c 5/54, G03c 7/00,G03c l/84 [58] Field of Search 96/3, 29 D, 84 R [56] References CitedUNITED STATES PATENTS 3,702,244 ll/l972 Bloom et al. 96/3 PrimaryExaminer-Norman G. Torchin Assistant Examiner-Alfonso T. Suro PicoAttorney-Charles Mikulka et al.

[5 7] ABSTRACT This invention relates to a class of phthalein indicatordyes useful as optical filter agents in photographic processes toprotect a selectively exposed photosensitive material from furtherexposure during processing in the presence of incident light. Such dyescomprise 3,3-disubstituted phthalides and 3,3-disubstituted naphthalideswherein the 3,3 substituents are phydroxy carbocyclic aryl radicalswherein one or both of the radicals possess a -CHz-NRR' group ortho tothe p-hydroxy group and the -CH2--NRR group(s) is capable of renderingthe indicator dye substantially non-diffusible in aqueous solution.

105 Claims, No Drawings

2. A process as defined in claim 1 wherein said indicator dye isinitially disposed in said processing composition having a pH at whichsaid indicator dye is light-absorbing, said processing composition beingapplied to said photosensitive layer and said composition containingsaid indicator dye being separated from the photosensitive layersubsequent to substantial image development.
 3. A process as defined inclaim 1 wherein said indicator dye is retained in said element and isrendered ineffective to prevent viewing of the final image subsequent tosubstantial image development by adjusting the pH of said indicatordye''s environment to a value at which it is substantiallynon-light-absorbing.
 4. A process as defined in claim 3 wherein saidindicator dye is initially present in a processing composition permeablelayer at a pH value at which it is substantially non-light absorbing,said layer being coextensive with at least one surface of saidphotosensitive layer and said processing composition applied theretohaving a pH at which said indicator dye is light-absorbing.
 5. A processas defined in claim 1 wherein said layer of photosensitive material is asilver halide layer.
 6. A process as defined in claim 1 wherein saidindicator dye is a 3,3-disubstituted phthalide.
 7. A process as definedin claim 6 wherein said 3,3 substituents are two benzindol-2-ylradicals.
 8. A process as defined in claim 6 wherein said 3,3substituents are two benzindol-3-yl radicals.
 9. A process aS defined inclaim 6 wherein said indicator dye is di-benzindol-2-yl7-carboxyphthalide.
 10. A process as defined in claim 6 wherein saidindicator dye is di-benzindol-3-yl 7-carboxyphthalide.
 11. A process offorming photographic diffusion transfer images which comprises, incombination, the steps of: a. exposing a photographic film unit whichcomprises a plurality of layers including an opaque support layercarrying a photosensitive silver halide layer having associatedtherewith a compound capable of providing as a function of developmentan imagewise distribution of an image-forming material which isprocessing composition soluble and diffusible as a function of thepoint-to-point degree of exposure of said silver halide layer and adiffusion transfer process image-receiving layer adapted to receivesolubilized image-forming material diffusing thereto; b. contacting saidphotosensitive silver halide layer with an aqueous alkaline processingcomposition to provide an indicator dye in a form capable of absorbing apredetermined wavelength range of radiation actinic to saidphotosensitive material, said indicator dye being selected from a3,3-disubstituted phthalide and a 3,3-disubstituted naphthalide whereinsaid 3,3 substituents are selected from two benzindol-2-yl radicals andtwo benzidol-3-yl radicals. c. effecting thereby development of saidsilver halide emulsion; d. forming thereby an imagewise distribution ofdiffusible image-forming material, as a function of the point-to-pointdegree of emulsion exposure; and e. transferring, by diffusion, at leasta portion of said imagewise distribution of diffusible image-formingmaterial to said layer adapted to receive said material to provide animage therein; said indicator dye being present during development in aposition and quantity effective to absorb said wavelength range ofactinic radiation in an amount sufficient to prevent any substantialdecrease, as a result of performing said process in the presence ofincident actinic light within said wavelength range, in the maximumdensity of the image obtained by the transfer of said diffusibleimage-forming material.
 12. A process of forming transfer images asdefined in claim 11 wherein said indicator dye is disposed, at a pHbelow its pKa, in a separate processing composition permeable layer andsaid photosensitive silver halide layer is positioned intermediate saidopaque support and said layer containing said indicator dye.
 13. Aprocess of forming transfer images in color which comprises, incombination, the steps of: a. exposing a photographic film unit which isadapted to be processed by application of pressure to release anddistribute a processing composition and which includes, in combination,a photosensitive element comprising a composite structure containing, asessential layers, in sequence, a first support layer opaque to incidentactinic radiation; a photosensitive silver halide layer havingassociated therewith a compound capable of providing as a function ofdevelopment an imagewise distribution of a dye image-forming materialwhich is processing composition soluble and diffusible as a function ofexposure of the photosensitive silver halide layer to actinic radiation;a polymeric layer dyeable by said dye image-forming material; a secondsupport layer transparent to indicent actinic radiation; and meanssecuring said layers in substantially fixed relationship; means forinterposing a reflecting agent and an indicator dye capable of absorbingincident radiation within a predetermined wavelength range actinic tosaid photosensitive layer at a pH above its pKa intermediate saiddyeable polymeric layer and said photosensitive silver halide layer andassociated dye image-forming material subsequent to photoexposure ofsaid film unit, said indicator dye being selected from a3,3-disubstituted phthalide and a 3,3-disubstituted naphthalide whereiNsaid 3,3 substituents are selected from two benzindol-2-yl radicals andtwo benzindol-3-yl radicals; a rupturable container retaining an aqueousalkaline processing composition possessing a pH above the pKa of saidindicator dye fixedly positioned and extending transverse a leading edgeof said photosensitive element to effect unidirectional discharge of thecontainer''s processing composition intermediate said dyeable polymericlayer and the photosensitive silver halide layer next adjacent theretoupon application of compressive force to said container: b. applyingcompressive force to said rupturable container to effect unidirectionaldischarge of the container''s processing composition intermediate saiddyeable polymeric layer and said photosensitive silver halide layer; ceffecting thereby substantial development of said silver halide layerand disposition of said reflecting agent and said indicator dye at a pHabove its pKa intermediate said dyeable polymeric layer and saidphotosensitive silver halide layer; d. as a result of said development,forming an imagewise distribution of diffusible dye image-formingmaterial, as a function of the point-to-point degree of exposure of saidphotosensitive layer; e. transferring, by diffusion, at least a portionof said imagewise distribution of diffusible dye image-forming materialto said dyeable polymeric layer to provide a dye image thereto; and f.maintaining said composite structure in tact subsequent to saidprocessing, said indicator dye being present in a quantity effective toabsorb said wavelength range of incident radiation in an amountsufficient in combination with said reflecting agent, to prevent anysubstantial decrease, as a result of performing said process in thepresence of incident actinic light within said wavelength range, in themaximum density of the image obtained by the transfer of said diffusibleimage-forming material.
 14. A process of forming transfer images incolor as defined in claim 13 wherein said indicator dye is initiallydisposed at a pH below its pKa in an aqueous alkaline processingcomposition permeable layer of said photosensitive element intermediatesaid dyeable polymeric layer and said silver halide layer, and saidrupturable container containing said aqueous alkaline processingcomposition possessing a pH above the pKa of said indicator dye isfixedly positioned and extends transverse a leading edge of saidphotosensitive element to effect unidirectional discharge of theprocessing composition intermediate said dyeable polymeric layer andsaid layer containing said indicator dye upon application of compressiveforce to said container and including the step of discharging saidprocessing composition, subsequent to exposure of said photosensitiveelement, intermediate said dyeable polymeric layer and said layercontaining said indicator dye.
 15. A process of forming transfer imagesin color as defined in claim 13 wherein said reflecting agent istitanium dioxide and said indicator dye and said titanium dioxide areinitially disposed in said aqueous alkaline processing composition asretained in said rupturable container.
 16. A process of forming transferimages in color as defined in claim 13 wherein said photosensitiveelement includes at least one acid reacting polymeric layer positionedintermediate at least one of (a) said first opaque layer and thephotosensitive silver halide layer next adjacent thereto, and (b) saidsecond transparent layer and the dyeable polymeric layer next adjacentthereto, and contains sufficient acidifying function to effect reductionof said aqueous alkaline processing composition from a pH above to a pHbelow the pKa of said indicator dye and including the step oftransferring, by diffusion, subsequent to substantial transfer dye imageformation, a sufficient portion of the ions of said processingcomposition to said polymeric acid layer to thereby reduce said pH to apH below said pKa.
 17. A process of forming transfer images in color asdefined in claim 16 wherein said dye-image forming material comprises adye which is a silver halide developing agent and said photosensitivelayer is a silver halide emulsion.
 18. A process of forming transferimages in color as defined in claim 17 wherein said photosensitiveelement comprises at least two selectively sensitized silver halideemulsion layers, each of said layers having associated therewith animage-forming dye, which is a silver halide developing agent, ofpredetermined color, and is soluble and diffusible, in aqueous alkalineprocessing composition as a function of the point-to-point degree ofexposure of the respective emulsion associated therewith.
 19. A processof forming transfer images in color as defined in claim 13 wherein saidphotosensitive element comprises three selectively sensitized silverhalide emulsion layers on said support, in sequence, a red-sensitivesilver halide emulsion layer having associated therewith a cyanimage-forming dye; a green-sensitive silver halide emulsion layer havingassociated therewith a magenta image-forming dye; a blue-sensitivesilver halide emulsion layer having associated therewith a yellowimage-forming dye; each of said cyan, magenta and yellow image-formingdyes being silver halide developing agents and soluble and diffusible insaid aqueous alkaline processing solution.
 20. A process as defined inclaim 13 wherein said indicator dye is a 3,3-disubstituted phthalide.21. A process as defined in claim 20 wherein said 3,3 substituents arebenzindol-2-yl radicals.
 22. A process as defined in claim 20 whereinsaid 3,3 substituents are benzindol-3-yl radicals.
 23. A process asdefined in claim 13 wherein said indicator dye is di-benzindol-2-yl7-carboxyphthalide.
 24. A process as defined in claim 13 wherein saidindicator dye is di-benzindol-3-yl 7-carboxyphthalide.
 25. Aphotographic film unit which comprises a plurality of layers including asupport layer carrying on one surface, in order a layer ofphotosensitive material and a layer comprising an indicator dye disposedat a pH below its pKa selected from a 3,3-disubstituted phthalide and a3,3-disubstituted naphthalide wherein said 3,3 substituents are selectedfrom two benzindol-2-yl radicals and two benzindol-3-yl radicals.
 26. Aphotographic film unit as defined in claim 25 wherein saidphotosensitive material is silver halide.
 27. A photographic film unitas defined in claim 25 wherein said silver halide layer has associatedtherewith a silver halide developing agent.
 28. A photographic film unitas defined in claim 25 wherein said silver halide layer has associatedtherewith a dye-providing compound capable of providing as a function ofdevelopment an imagewise distribution of a dye image-forming materialwhich is processing composition soluble and diffusible as a function ofthe point-to-point degree of exposure of said silver halide layer.
 29. Aphotographic film unit as defined in claim 28 which is adapted to beprocessed by application of pressure to release and distribute aprocessing composition and which comprises, in combination: aphotosensitive element including a composite structure containing, asessential layers, in sequence, a first support layer opaque to incidentactinic radiation; at least two selectively sensitized silver halidelayers, each having associated therewith an image-forming dye which is asilver halide developing agent of predetermined color, each of said dyesbeing soluble and diffusible in alkaline processing composition as afunction of the point-to-point degree of exposure of the respectivesilver halide associated therewith, a polymeric layer dyeable by saiddye; a second support layer transparent to incident actinic radiation;and means securing said layers in substantially fixed relationship; arupturable container retaining an alkaline processing compositioncontaining reflecting agent fixedly positioned and extending transversea leading edge of said photosensitive element to effect unidirectionaldischarge of said container''s processing composition between saiddyeable polymeric layer and the photosensitive silver halide layer nextadjacent therto upon application of pressure to said container; and anindicator dye capable of absorbing incident radiation within apredetermined wavelength range actinic to said silver halide disposed inat least one of said processing composition and, at a pH below its pKa,in a layer intermediate said photosensitive silver halide layer and saidsecond support layer transparent to incident actinic radiation, saidindicator dye being selected from a 3,3-disubstituted phthalide and a3,3-disubstituted naphthalide wherein said 3,3 substituents are selectedfrom two benzindol-2-yl radicals and two benzindol-3-yl radicals.
 30. Aphotographic film unit as defined in claim 29 including at least oneacid reacting polymeric layer positioned intermediate at least one ofsaid first opaque layer and the photosensitive silver halide layer nextadjacent thereto, and said second transparent layer and the dyeablepolymeric layer next adjacent therto, said polymeric acid layercontaining sufficient acidifying function to effect reduction of saidprocessing composition from a first pH at which said image-forming dyeis substantially soluble and diffusible to a second pH at which saidimage-forming dye is substantially nondiffusible.
 31. A photographicfilm unit as defined in claim 30 wherein said reflecting agent takentogether with said indicator dye are adapted to prevent further exposureof the selectively exposed silver halide layer during processing in thepresence of radiation within said predetermined wavelength range actinicto the silver halide layer and incident on the surface of the film unitopposite to the opaque support layer.
 32. A photographic film unit asdefined in claim 31 wherein said photosensitive element includes, asessential layers, in sequence, from said opaque support layer, analkaline solution permeable polymeric layer containing a cyan dye; ared-sensitive silver halide emulsion layer; an alkaline solutionpermeable polymeric layer containing a magenta dye; a green-sensitivesilver halide emulsion layer; an alkaline solution permeable polymericlayer containing a yellow dye; a blue-sensitive silver halide emulsionlayer, each of said cyan, magenta and yellow dyes being silver halidedeveloping agents and being soluble and diffusible, in aqueous alkalinesolution at said first pH and substantially insoluble in aqueousalkaline solution at said second pH.
 33. A film unit as defined in claim29 wherein said indicator dye is a 3,3-disubstituted phthalide.
 34. Afilm unit as defined in claim -yl wherein said 3,3 substituents arebenzindol-2yl radicals.
 35. A film unit as defined in claim 33 whereinsaid 3,3 substitutent are benzindol-3-yl radicals.
 36. A film unit asdefined in claim 29 wherein said indicator dye is di-benzindol-2-yl7-carboxyphthalide.
 37. A film unit as defined in claim 29 wherein saidindicator dye is di-benzindol-3-yl 7-carboxyphthalide.
 38. Aphotographic processing composition comprising an aqueous alkalinesolution of a viscosity imparting reagent, a light-reflecting agent andan indicator dye selected from a 3,3-disubstituted phthalide and a3,3-disubstituted naphthalide wherein said 3,3 substituents are selectedfrom two benzindol-2-yl radicals and two benzindol-3-yl radicals.
 39. Aphotographic processing composition as defined in claim 38 whichadditionally contains a silver halide developing agent.
 40. Acomposition as defined in claim 38 wherein said indicator dye is a3,3-disubstituted phthalide.
 41. A composition as defined in claim 40wherein said 3,3 substituents are benzindol-2-yl radicals.
 42. Acomposition as defined in claim 40 wherein said 3,3 substituents arebenzindol-3-yl radicals.
 43. A composition as defined in claim 38wherein said indicator dye is di-benzindol-2-yl 7-carboxyphthalide. 44.A composition as defined in claim 38 wherein said indicator dye isdi-benzindol-3-yl 7-carboxyphthalide.
 45. A composition as defined inclaim 38 wherein said aqueous alkaline solution has a pH above the pKaof said indicator dye.